Improvement in dental rubber-dam punches



UNITED STATES JOHN RIX, OF FORT MADISON, AND PIERCE T. SMITH, OF BURLINGTON PATENT OFFICE.

IOWA.

IMPROVEMENT IN DENTAL RUBBER-DAM PUNCI-lES.

Specification form ng part of Letters Patent No. 175,505, dated March 2B, 1876; application filed October 22, 1875.

The object of the invention is to cut holesof any desired size in the rubber dam so much used by dentists.

The invention,k consists of a device in shape like a pair of shears, one blade, a, being round and straight; the other blade, c, bends outward from near the joint, and, describing an arc, meets, when closed, the blade a at its end. The end of the blade c is bent outward at an angle, so that when closed upon the blade a it is parallel with it. This end is round and supplied with a flanged tliimble, b, made to slide, and kept in position either by a setserew or by a slot eutin the end of the thimble, then closed a trifle, and sprung on. The

flange ofthe thimble is made with a sharp cutting-edge.

To operate the instrument, take it in the right hand like a pair of common shears, open the instrument, and, with the left hand, stretch a piece of rubber dam tightly over the end ot' the blade a, close the instrument, which brings the sharp cutting-flange of the thimble b against the rubber dam. The effect is to form a perfectly round hole in the rubber dam. The size ot' the hole can be varied by moving the thimble, a smaller hole being made by moving the cutter toward the end, and a larger hole being made by moving it from the end,

We claim- In an instrument for punching rubber dams, the combination ofthe straight blade a, the curved blade e, carrying an adjustable anged cutting-thimble, all as and for the purposes described.

JOHN RIX. PIERCE T. SMITH. Witnessed by us:

THEoDoR NIEMANN, R. L. COCHRAN. 

